A smart window is a window which can freely control transmittance of solar light, and is called an electron curtain, a transmittance switchable glass, or an illuminated glass.
The smart window consists of, for example, a light transmittance control layer capable of controlling the transmittance of light, and a driving circuit controlling the light transmittance by applying a signal to the light transmittance control layer. The smart window configured as described above is manufactured to transmit light from an entire surface thereof or not to transmit light according to a state of an applied voltage, and has various contrasts by controlling the transmittance.
Recently, as attention to an energy-saving smart window increases, a technique of forming a low emissivity (low-e) coating layer or an electrochromism (EC) coating layer on the smart window has been developed, but the conventional art (Korean Laid-Open Patent Publication No. 2008-0040439) has a limit to satisfy ensuring of a view according to the change in solar light, effective prevention of ultraviolet rays and infrared rays and prevention of leakage of heating generated inside at the same time.